JPS5854558B2 - Call path control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication path control system when a switch element made of a PNPN type semiconductor is used as a communication path switch in an exchange, a key telephone device, a line concentrator, or the like.

Conventionally, when a PNPN switch is used as a communication path switch, it is necessary to apply a control current to its control terminal at all times or immediately after disconnection because noise or other factors cause the switch to be disconnected due to instantaneous interruptions in the communication current.

In this case, the means for applying voltage to the control terminal is (1
) A method of applying a DC control current, or (2) a method of applying a control current only at the time of operation (at the start of ignition),
After the switch is energized, the energizing current is monitored, and when the PNPN switch is turned off for some reason and the current is cut off, the control current is applied again, or (3) the method described above. There is a method of applying a time-division pulsed current instead of the DC control current described in (1).

However, all of these methods have drawbacks and are not practical.

That is, the method (1) is based on the aforementioned NPN switch 11
One memory element is required per fixed unit, which is disadvantageous in terms of cost and mounting space.Method (2) requires a voltage drop for current detection, so it is not a problem for local battery type equipment, but This is disadvantageous for equipment that supplies communication current directly from a central office exchange, etc., and in method (3), when the communication path switch circuit is like the circuits shown in FIGS. 1A and B, for example,
This is inconvenient as noise is generated.

Here, 1 is a current-coupled PNPN switch, 2, 3, 4
．． 5 is bridge-coupled by an optically coupled PNPN switch.

6°7 is a transformer.

The operation of the circuit in Figure 1 is that by applying a pulse current to its control terminal, noise is generated in the communication circuit from the conducting switch 1 in A, and the non-conducting switches 2 and 4 are connected to the trigger gate in B. The applied signal causes a dark current to flow between the anode and cathode, causing noise in the communication circuit.

There is also a method using voltage detection instead of current detection in method 2, but this requires the resistance value of the detection circuit to be several hundred kilograms or more, which is not practical.

As mentioned above, the conventional communication line switch control system using a PNPN switch has many problems, and is particularly effective in the case of a circuit system in which the communication current is directly supplied from the station as shown in Figure 1B. There was no way.

In order to eliminate these drawbacks, the present invention uses an inexpensive time-division pulse drive method as a control signal, and as a noise countermeasure, the station line The time division pulse is transmitted to the PNPN only when acquisition information is arriving by the telephone and the PNPN switch is off.
This provides a communication path control method that controls the voltage applied to the control terminal of the switch.

The present invention will be explained in detail below with reference to the drawings.

FIG. 2 is an example of a configuration diagram of the present invention, in which 1 is a communication path switch, 2 is a gate circuit, 3 is a time-division pulse generation circuit,
4 is a switch circuit, 5 is a voltage detection circuit, and 6 is a telephone circuit.

The operation of this circuit is as follows.

When information for the telephone 6 to make a call or respond to an incoming call on the central office line, such as hook switch information, is applied to the time-division pulse generation circuit 3, a required output signal is output at the seventh circuit and applied to the control terminal of the switch circuit 4. and close the switch,
The voltage detection circuit 5, which guides the voltage of the office line to the voltage detection circuit 5, is configured to output an output signal when a voltage equal to or higher than a preset value, for example, about 20 V, is applied to its input terminal.

In addition, the output signal of the time division pulse generation circuit 3 is sent to the gate circuit 2.
is applied to one input terminal of

This gate circuit 2 applies the output to the control terminal of the communication path switch 1 only when the output signal of the voltage detection circuit 5 is applied to the other input terminal, makes it energized, and connects the central office line to the telephone circuit. Connect to 6.

As the communication current flows through the telephone circuit 6, the voltage of the office line decreases.

This value is usually after lovM and is less than the above-mentioned set value, so the output of the voltage detection circuit 5 is stopped and the output of the gate circuit 2 is also raised.

Here, in order to reduce call loss during a call, the input resistance of the voltage detection circuit 5 is configured to have a high resistance when the voltage value is lower than the set value.

This is possible with non-linear elements such as Zener diodes.

During a call using the telephone circuit 6, call loss due to insertion of the voltage detection circuit 5 can be reduced.

Next, when the communication path switch 1 is disconnected during a call, the above-mentioned operation is repeated, an output signal from the gate circuit 2 is obtained, and the communication path switch 1 is restarted.

As explained above, as a means of obtaining the conditions for restriking the PNPN switch, the present invention maintains the loop resistance of the central office line at a high resistance during standby (when there is no call or response) and during calls. This is made possible by detecting the voltage between the lines.

FIG. 3 shows an example of a circuit diagram of the present invention.

In Figure 3, 1 to 6 are the same as in Figure 2, and 11 to 6 are the same as in Figure 2.
14 and 43 are PNPN type semiconductor elements, 15.45 is 1
A light emitting element for optically coupling and driving 1 to 14 and 43, 21 is a NAND gate, 16,44°51 is a resistor, 41 is a diode bridge, 42°55 is an inverter, 52 is a Zener diode, and 53 is a photocoupler. ,
54 is a delay circuit, and % Ll jL2 is a station line connection terminal.

In addition, the * symbol performs necessary processing on the hook information etc. sent from the telephone set 6, and the central office line L1. This is an input terminal for inputting L2 to the time division pulse generation circuit 3 as information to be captured.

The operation of the embodiment of FIG. 3 is as follows.

When central office line acquisition information is input to the time-division pulse generation circuit 3 by lifting the handset of the telephone circuit 6, the output signal causes a current to flow through the optically coupled light emitting element 45 of the PNPN semiconductor element 43 via the inverter 42. , PNPN semiconductor element 43
conducts.

As a result, for example, as a signal, Ll (+) and L2 (
→, the voltage applied to Ll and L2 causes the foot coupler 53 to be
→Diode bridge 41→PNPN semiconductor element 43→
Resistor 51 → Schener diode 52 → input side of photocoupler 53 → diode bridge 41 → terminal L2]
Current flows through ports 11 and 11, turning the output on.

Next, the output of the photo coupler 53 passes through a delay circuit 54 and an inverter 55, and applies an H level to one terminal of the NAND gate 21.
The output of is applied to the other terminal of the gate 21, and due to the above-mentioned H level, a time-division pulse signal is output to the output, and the signal causes current to flow through the light emitting element 15, and the PNP
N semiconductor elements 11 and 14 are made conductive.

When 11゜14 becomes conductive, the voltage between L terminal and L2 terminal becomes [
Terminal L1 → PNPN semiconductor element 11 → Telephone circuit 6 → P
NPN semiconductor element 14→terminal L2] is formed by forming a DC loop.

As a result, the route of the photocoupler 53 is cut off by the Zener diode 52, the output of the inverter 55 is stopped, the H level of the gate 21 becomes L level, the output is blocked, and the current of the light emitting element 15 is will be cut off.

As a result of the above operation, during a call, the drive current to the PNPN semiconductor element 15 is cut off, but the conduction of the call loop is maintained due to the self-holding characteristics of the PNPN elements 11 and 14.

As explained above, the present invention can be used in small-scale PABXs, key telephone devices, line concentrators, etc.
In a system in which current is supplied directly from the central office exchange as the communication current, a control system using a PNPN semiconductor switch element for the communication path is compact, low cost, and
This method provides a method with good performance, and has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a communication line circuit system to which the present invention is applied, and FIG. 2 is a block diagram showing an embodiment of the present invention.
FIG. 3 is a circuit diagram showing an example of a circuit according to an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A communication path in which the on/off of a communication path switch composed of a PNPN type semiconductor device inserted between a telephone line and a telephone set is controlled by a time-division pulse signal output from a time-division pulse generation means. In the control method, a switch means is turned on when a signal for capturing the telephone line arrives and is connected in parallel with the call path switch in order to identify whether the telephone line is idle or in a busy state; a voltage detection circuit connected to the telephone line via a switch means; a time-division pulse generating means controlled by the output of the detection circuit to turn on the telephone line switch; and the telephone line. and a gate circuit inserted between the gate terminal of the switch and a high voltage higher than a predetermined setting voltage from the telephone line to the detection circuit when the capture signal arrives and the telephone line is idle. The gate circuit is controlled by the output detected by the detection circuit when a voltage is applied, and the time-division pulse is input to the gate circuit, and when the communication path switch is turned on, the voltage is detected. A communication path control system characterized in that the output of the circuit is cut off to prevent the time-division pulse from inputting to the gate terminal. 2. When the input voltage is lower than the set voltage value, the input resistance is increased. The communication path control system according to claim 1, characterized in that the voltage detection circuit is configured as a resistor.3. A communication path control system according to claim 1, characterized in that: